fixed usage

src/main_utils.cpp

@@ -176,6 +176,7 @@ cout<<"	           non-considered reads are  written into output file(s) with"<<
 cout<<"	           extension undefined.fastq (default: 1)"<<endl;
 cout<<" -v         verbose mode"<<endl;
 cout<<" -h         prints this message and exit"<<endl;
+exit(status);
 }
 
 /*